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Galina Goren, James Elder; Visual Distortions Induced by Simple and Complex Shapes. Journal of Vision 2015;15(12):531. doi: 10.1167/15.12.531.
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© ARVO (1962-2015); The Authors (2016-present)
We have recently reported that natural contours induce perceptual distortions in neighbouring regions of visual space (Goren & Elder VSS2013). However, the magnitude of these distortions has yet to be quantified, and the precise conditions necessary to generate them remain unclear. Here we employ a new quantitative method to measure the size of these perceptual distortions, and systematically vary the complexity of the inducing contours to determine whether contour shape modulates their genesis. Methods. The stimulus consisted of a collinear triplet of dots orthogonal to a nearby contour. Observers used a mouse to move the central dot along the virtual line connecting the flankers until it was perceived to bisect them. 11 positions of the dot probe were evaluated, ranging from one side of the contour to the other. Contours included horizontal and vertical lines and line segments, circles and arcs of circles, as well as natural animal shapes. Results. The induced distortion of perceptual space was found to be highly similar for both simple and complex contours. Generally, space was perceived as compressed in the immediate vicinity of the contour and expanded at intermediate distances, and the magnitude of these distortions generally peaked at roughly 7 arcmin, or 0.8% of the half-width of our 2.8 deg dot probe. Space was generally undistorted at points distant from the contour. These findings suggest that the observed distortions may be determined by local properties of contours rather than global shape.
Meeting abstract presented at VSS 2015
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